Thin films that are transparent in the visible light range and have electrical conductivity are used for transparent electrodes in touch panels and advanced display systems such as liquid crystal displays and electroluminescence displays and also used for electromagnetic wave shielding or prevention of static charge of transparent products.
Concerning conventional transparent conductive thin films, the so-called conductive glass is well known, which includes a glass member and an indium oxide thin film formed thereon. Since the base member of the conductive glass is made of glass, however, it has low flexibility or workability and cannot be used for certain purposes.
In recent years, therefore, transparent conductive films using various types of plastic films such as polyethylene terephthalate films as their substrate have been used, because of their advantages such as good impact resistance and light weight as well as flexibility and workability.
However, touch panels using such conventional transparent conductive thin films have a problem in which Newton's rings are formed when touch panels are pressed by fingers or the like. In order to prevent the formation of such Newton's rings, for example, it is proposed that a transparent conductive film should include a coating layer with a thickness of 1 to 3 μm between a transparent plastic and a transparent conductive thin film, wherein a filler with an average particle size of 1 to 4 μm is contained at a number average density of 500 to 3000/mm2 in the coating layer (see Patent Literature 1 listed below) and that the transparent conductive film to be used should include a transparent resin film and a 20 to 55 nm-thick silicon oxide thin film layer and a transparent thin film electrode layer formed in this order on the resin film, wherein the surface of the transparent thin film electrode layer has an average centerline roughness (Ra) of 0.05 to 2 μm and a maximum height (Rmax) of 0.6 μm to 2.5 μm (see Patent Literature 2 listed below). The formation of Newton's rings can be reduced in a touch panel using the proposed transparent conductive film as a touch panel electrode sheet.
On the other hand, transparent conductive films have a problem in which their conductive thin films have poor scratch resistance or bending resistance so that they can be scratched during use to have increased electric resistance or to suffer from disconnection. When used in a touch panel, a pair of conductive thin films placed opposite to each other with spacers interposed therebetween are strongly brought into contact with each other by pressing and tapping from one panel plate side. Therefore, it is desired that transparent conductive films should have high durability to pressing and tapping, specifically tapping resistance, particularly pen input durability. However, the transparent conductive film in which the transparent conductive thin film has controlled irregularities in order to prevent Newton's rings as described in the patent literature cannot have satisfactory durability. Therefore, such a transparent conductive film has a problem in which when it can suppress the formation of Newton's rings, it rather has poor durability so that it can form a touch panel with a short life.
Conventional transparent conductive films also have the problem of low transparency, because the surface of their thin film has high light reflectance. Even when transparent conductive thin films have controlled irregularities as described above, however, display characteristics with respect to glare, image formability and so on are not satisfactory.    Patent Literature 1: Japanese Patent Application Laid-Open (JP-A) No. 10-323931    Patent Literature 2: JP-A No. 11-250764